The construction and maintenance of multi-story buildings, such as high-rise office and residential buildings is accomplished, in part, through the use of multi-point suspended scaffolds. Such buildings are provided, typically along their upper roof edge, with a plurality of spaced cantilever or outrigger beams. These beams are pivotable, about a suitable pivot axis at the building edge, or are slidable into a cantilever position in which the beams extend out from the walls of the building. These beams are typically spaced apart at a uniform distance and are usable to support the suspended scaffolds which are used by masons, glaziers, window washers and similar building repair and maintenance personnel.
Scaffolds are suspended by cables from the cantilever outrigger beams and are movable vertically with respect to the walls of the building or other structures by winches. These winches are attached to the frame of the scaffolds and may be manually operated or may be powered by electricity or the like. In use, the winches are operated to raise or lower the scaffold to the appropriate work level.
One or more workmen will use the scaffold assembly as a work platform from which to perform the masonry work required in the construction of the building, the installation of window walls that may be utilized in the building construction, the application of metal fascia pieces, the installation of caulking and similar tasks. It is imperative that the scaffolds be provided with sufficient structural rigidity and strength to insure that the scaffold will not collapse under load and will not fall apart in the event of, for example, one of the cables failing or slipping on its associated winch. Various government codes and regulations have dictated that a scaffold be able to meet certain safety standards with respect to strength, durability and failure resistance.
In prior scaffolds, the structures have been complex and cumbersome. A large number of components have had to be assembled to form the resulting scaffold. Since the typical scaffold is assembled at a point of use, used over a finite period of time, and is then disassembled and taken to a new point of use, the assembly and disassembly times that are required are of importance. In prior scaffolds, the use of a large number of individual components has required a substantial amount of time to accomplish the assembly and disassembly of the scaffolds. The expenditure of such a large amount of time is costly.
Since each scaffold is typically suspended at a distance above the ground and must support the weight of one or more workmen and their equipment and supplies, the scaffold must have sufficient structural strength and rigidity to accomplish this task. In prior systems, this has tended to result in the use of large, strong components which also have a great deal of weight. This weight of the scaffold itself is a component of the overall weight that can be supported from the cantilever outrigger beams by the suspending cables. The greater the weight of the scaffold itself, the less payload, in the form of men, equipment and supplies that can be supported by the scaffold. The use of these heavy scaffold components, while providing the needed structural rigidity and strength, also reduces the weight of the workmen and supplies that each scaffold can carry. In addition, a heavy scaffold structure requires more labor to assemble, disassemble and transport. The prior scaffolds have thus been expensive to put together, to take apart, and to transport.
In the unlikely event of the failure of one or more of the suspension cables, the scaffold being supported by these cables must retain its structural integrity. It may tilt or drop at the point where the supporting cable has slipped or broken, but it cannot fail structurally. The scaffold must remain assembled at all times. In the past, this has again given rise to scaffold structures which have required a number of braces. While the use of such an arrangement of a plurality of braces has insured that the scaffold will maintain its structural integrity, it has also added to both the complexity and the weight of the resultant scaffold. As noted above, since virtually all scaffolds are assembled on a particular job site, used for a finite length of time at that job site and then taken apart and transported to another job site, the use of a large number of braces and reinforcing rods has added to the time needed for assembly and take down and has also added substantial weight to the scaffolds.
Various government regulations require that all scaffolds have certain features which are intended to aid in maintaining the safety of the workers who are using the scaffold. One of these requirements is the provision of toeboards that are used to prevent the toes or feet of the workmen from extending out past the working surface of the scaffold. This is important in the prevention of injuries. Another is the provision of guard rails at specified locations. Mesh is also typically required to prevent the likelihood of objects falling off the scaffold. However, the provision of these government-mandated toeboards, guard rails and retention mesh has required the installation of additional elements in the assembly of each scaffold. In the prior scaffolds, the sole purpose of the toeboard was to act as a guard for the feet of the workers. Guard rails were also thought of as being only for protection. The same was true with respect to retention mesh or netting. No thought was given to the possible use of these toeboards, guard rails and mesh as structural components of the scaffold. The result again has been an unduly complex structure that is time-consuming to assemble and to take apart and that is heavy and cumbersome to transport between job sites.
Prior scaffold assemblies have tended to be heavy, cumbersome structures that are labor intensive to assemble and to disassemble. They have used components that provide structural rigidity at the expense of reduced weight. While they have been safe and have complied with the applicable government rules and have met the necessary standards, they have not done so using a structure that is lightweight, and structurally uncomplicated. The multi-point suspended scaffold in accordance with the present invention, as will be set forth subsequently, overcomes these limitations of the prior art and is a substantial advance in the art.